Residual Volume Responsiveness Testing May Improve the Detection of Reversible Airway Obstruction in Asthma.

BACKGROUND: Residual volume responsiveness to bronchodilator administration has been observed in subjects with chronic obstructive pulmonary disease. However, the prevalence of residual volume (RV) responsiveness has not been formally studied in asthma. OBJECTIVE: To identify the prevalence and magnitude of RV responsiveness in asthma. METHODS: Physician-diagnosed adult subjects with asthma on treatment for >12 months were prospectively recruited to perform spirometry and measurement of lung volumes using body plethysmography before and after administration of 360 µg of albuterol. RESULTS: Among 120 subjects, 76% were women. The ethnic composition was 64% Caucasian, 32% Hispanic, and 13% African American. The mean age was 52 ± 15 years. The mean duration of asthma was 16 ± 15 years. The mean RV% responsiveness was -7.74 ± 14. Whereas patients with the lowest baseline forced expiratory volume in 1 second (FEV1) value showed the highest mean responsiveness (P = .001), the baseline RV value had minimal influence on RV responsiveness. Using -7.74% to define significant RV responsiveness, and ≥12% and ≥200 mL to define significant FEV1 responsiveness, more subjects showed isolated RV responsiveness (37%) compared with 6% with isolated FEV1 responsiveness and 14% with both FEV1 and RV responsiveness (P = .04). There was a minimal correlation between FEV1 responsiveness and RV responsiveness (r = 0.17, P = .06). The RV responsiveness was significantly associated with the wheeze score (P = .006) and dyspnea score (P = .029). CONCLUSION: The addition of RV responsiveness testing to spirometry based responsiveness testing can improve the identification of reversible airway obstruction in asthma. RV responsiveness may be useful in monitoring symptoms associated with air trapping in asthma.

Air Trapping Correlates With Increased Frequency of Albuterol Use and Severity of Wheeze in Persistent Asthma.

BACKGROUND: Symptoms of asthma have been shown to correlate poorly with spirometric variables of obstruction. We hypothesized that lung volume measurements might correlate with symptoms and frequency of rescue inhaler use in asthma. METHODS: Patients with persistent asthma on treatment for ≥12 months were enrolled from university-based clinics. The association between lung volumes, spirometry, asthma symptoms, and rescue inhaler use were explored by using linear modeling. RESULTS: Among the 120 subjects, 76% were women. The mean age ± SD was 52 ± 15 y. With regard to ethnicity, 64% of the subjects were caucasian, 23% were Hispanic, and 13% were African-American. Twenty-one percent of the subjects reported chest pain. There was no significant correlation between asthma symptoms or rescue inhaler use to spirometry indices of obstruction. The residual volume percent of predicted showed a significant association with the wheeze score (r = 0.32, P = .001) and frequency of rescue inhaler use (r = 0.35, P ≤ .001). Linear contrast analysis showed that the mean wheeze score (P = .003) and frequency of rescue inhaler (P = .007) use increased linearly from the lowest to the highest quartiles of residual volume. Furthermore, multiple regression analysis showed an association only to the residual volume percent predicted value to the pressurized metered-dose inhaler score and the wheeze score. CONCLUSIONS: Frequent albuterol use and wheezing may be a sign of unrelieved air trapping. Chest pain is a unique symptom in persistent asthma, and the pathogenesis requires further studies. Lung volume measurement added to routine spirometry can help identify patients with asthma and with air trapping.

Patterns of pulmonary dysfunction in asbestos workers: a cross-sectional study.

BACKGROUND: Restrictive patterns of pulmonary function abnormalities associated with asbestos exposure are well described. Studies are less consistent, however, regarding the association of asbestos inhalation with airway dysfunction and obstructive impairment. METHODS: We compared pulmonary function test results between 277 chrysotile exposed workers (22% non-smokers) and 177 unexposed controls (50.3% non-smokers). Information on exposure and smoking were collected using a standardized questionnaire. Standardized spirometric and DCLO Measurement methods were utilized. CXRs were read based on ILO pneumoconiosis guidelines. RESULTS: Asbestos exposed subjects had significantly reduced FVC, FEV1, FEV1/FVC and DLCO. Restricting the analysis to non-smokers, asbestos workers still had about 3% lower FEV1/FVC ratio than controls, but this difference did not reach statistical significance. Among exposed workers, the presence of radiographic evidence of asbestosis further lowered FVC and DLCO but not FEV1/FVC compared to asbestos exposure without radiographic asbestosis. Additionally, smoking asbestos workers had significantly lower DLCO compared to non-smoking workers. CONCLUSION: Asbestos exposure, especially when radiographic evidence of interstitial fibrosis from asbestosis is present, leads to significant decreases in FVC, FEV1 and the DLCO. However, asbestos exposure alone is not significantly associated with a reduction of the FEV1/FVC. Smoking-asbestos workers had significantly lower DLCO than their non-smoking counterparts. Whether asbestos interacts with smoking additively or synergistically on DLCO needs further investigation. Similarly, further studies are needed to assess the progression and clinical significance of asbestos induced airway dysfunction.

Grand rounds: asbestos-related pericarditis in a boiler operator.

CONTEXT: Occupational and environmental exposures to asbestos remain a public health problem even in developed countries. Because of the long latency in asbestos-related pathology, past asbestos exposure continues to contribute to incident disease. Asbestos most commonly produces pulmonary pathology, with asbestos-related pleural disease as the most common manifestation. Although the pleurae and pericardium share certain histologic characteristics, asbestos-related pericarditis is rarely reported. CASE PRESENTATION: We present a 59-year-old man who worked around boilers for almost 30 years and was eventually determined to have calcific, constrictive pericarditis. He initially presented with an infectious exacerbation of chronic bronchitis. Chest radiographs demonstrated pleural and pericardial calcifications. Further evaluation with cardiac catheterization showed a hemodynamic picture consistent with constrictive pericarditis. A high-resolution computerized tomography scan of the chest demonstrated dense calcification in the pericardium, right pleural thickening and nodularity, right pleural plaque without calcification, and density in the right middle lobe. Pulmonary function testing showed mild obstruction and borderline low diffusing capacity. DISCUSSION: Based on the patient's occupational history, the presence of pleural pathology consistent with asbestos, previous evidence that asbestos can affect the pericardium, and absence of other likely explanations, we concluded that his pericarditis was asbestos-related. RELEVANCE TO CLINICAL PRACTICE: Similar to pleural thickening and plaque formation, asbestos may cause progressive fibrosis of the pericardium.